Reversible self-sharpening chisel



June 2, 1931.

J. l. M CORD REVERSIBLE SELF SHARPENING CHISEL Filed Dec. 26, 1929 vINVENTOR cfohn I.M== Cord BY M .QQJJQ;

ATTORNEY Patented a... 2, 1931 UNITED STATES;

JOEN' I. HOODED, 01 P550 ROBLES, CALIFORNIA, ASSIGNOB OI ONE-FOURTH 1'0BAY IB- LYON, OI PASO ROBLES, CALIFORNIA Y mn'asmnn snnr-snnnrnme cmsnnApplication filed December 26, 1929. Serial No. 416,481.

This invention relates to ground workin implements, and particularly tothe chise points adapted for use on sub-soilers, road plows and chiselcultivators, my improved 5 point being particularly useful where drywork is necessary or hard ground must be penetrated.

All such chisels as are now in use as far as I am aware are constructedin such a manner that as soon as the cutting edge becomes dull and wearsdown the chisel has a decided tendency to work out of the ground, and ofcourse does not then function as it should. This condition is reached soquickly that chisels cannot be used without being resharpened for evenone hour of continuous work. The labor and overhead costs due to thecontinuous resharpening and refitting operations necessary, and theconsequent tie-up of the machine, are therefore considerable.

The rincipal object of my invention is to avoid t e above veryobjectionable features by so shapingl the chisel as to cause the same 5to proper y old inthe ground for a long time as compared to the chisel,and so .that when t becomes dull and the point resent type of e cuttingedge has been worn back, reversing of the chisel changes this dull edgeinto a sharp one. This last edge in turn becomes dull in time and uponagain reversing the chisel or returning the same to its originalposition a sharp point is again pressed into the groun My im rovedchisel can therefore be efiicientl use until the available wearingportion 0 the same is entirely worn away, wlthout any manualresharpening or other attention being necessa except to reverse thesetting of the chisel v4o when required.

'To enable this reversing of the chisel to be easily carried out Ihaveprovided what I believe is a novel and automatic but easilyreleasable locking connection between the chisel and its supportingstandard.

A further object of the invention isto r0- vide a simple and inexpensivedevice an yet one which will be exceedi ly effective for "the purposefor which it isl gesigned.

These objects I accomplish by means of such structure and relativearrangement of parts .as will fully appear by a erusal of the followingspecificatlon and claims.

In the drawings similar characters of reference indicate correspondingparts inthe several views:

Fig. 1 is a perspective view of my improved chise Fig. 2 is a sideelevation of the chisel in its normal ground engaging position andbefore any wear has taken lace.

Fig. 3 1s a similar view s owing the chisel as somewhat worn awa and thecutting edge dulled from continue use in said original position.

Fig. 4 is a similar view of the chisel part1 in section showing thechisel as in the combtion illustrated in Fig. 3 but reversed inpositionrelative to the ground.

Fig. 5 is a fragmentary longitudinal plan PATEN errea 7 section of thechisel showlng the locking con- I chisel-may be considered asconstituting a relatively thick base portion 1 and a relatively thinpoint portion 2; said portions being however the same width in atransverse plane from end to end as shown in Fig. .1. The base portionis provided with a tapered socket 3 into which removably fits asimilarly shaped tongue 4 which projects with a slight downward anglefrom the supporting standard 5 of any suitable character. This tongue isdisposed so that the chisel will extend toward the ground at arelatively small slope or angle and is symmetrical in form relative toits longitudinal axis so that v the chisel will havesubstantially thesame slope whether in its normal or reversed position. The chisel isreinovably locked on' the tongue by a special device which will be 7 7full described later.

T e trouble w1th the ordinary chlsel points is that there is so muchfriction underneath the same that the oint is forced out of the groundas. soon as .t e initial chisel or wedgeshaped cutting edge A. becomesdulled and practically reversed as to its angular relation to theground.I

This objectionable feature I have entirely eliminated by forming theunder side of the point portion, for substantially the full length ofthe same, with a curvature B which 1s concave relative to a straightline G extending between the bottom of the base and the bottom of thepoint at the ti or edge A; said curved portion bein entire y above saidline. On the upper surface of the chisel on the other hand the pointportion is formed with a convex curve D, extending rearwardly from thecutting edge a certain distance, and then with a reversed or concavecurve or fiat bend E. The convex curve D is mainly above and the :bendor concave curve E is below, a straight line F drawn from the top of theedge A to the back of the base at the top. Thisarrangement or shape ofthe upper and lower contours of the chisel is what gives my improvedchisel its advantages over the ordinary form ofchisel. By reason of theconcave curvature of the under surface of the point portion, there is nomaterial friction on the under side of the chisel in operation such aswould tend to raise the point and cutting edge out of the ground. Thisin turn keeps all the weight of the chisel on the cutting edge, and thisremains true as the edge wears back along the point, owing to the lengthof said concave curvature. The holding of the point in the properdigging position in the ground is aided by the raised or convex topcurvature D, whose frictional contact with the ground tends to causetheforward portion of the chisel to be depressed. Also, this raised tortionbeing sub ected to a relatively great friction, it wears down as thecutting edge wears back. Therefore by the time the chisel has worn backuntil the setting of the cutting edge relative to the ground issubstantially parallel to the ground, as shown at H, the height orthickness of the chisel at that point has also been reduced a certainamount, so that the thickness of the chisel at the cutting edge whereverthis may be, is maintained substantially constant.

The bend. or curve E- serves two ends. The

- upper surface of the chisel havin a downward slope from the base towarthe cut-' ting edge, relative to the direct. line F between the ends ofthe chisel, enables the oint portion of the chisel. to enter the grounat a flatter angle as is desired, while maintainin .thedesired convexcurvature at the front on of the chisel, than would otherwise beossible. Also when the chisel is reverse position this'curve or bend Etakes the place of and serves the same purpose as does the curve orundercut B when the chisel is disposed in its normal position. This.will be A evident from a' comparison of Fig. .4 (the chisel whenreversed) with Fig. 2 (the chisel in its normal position) The point ofmajor depression of the bend E is disposed some curve B. Thus when thechisel is worn down considerably or as far is the edge '11, and thechisel is then reversed, said bend E occupies approximately the sameposition relative to the newcutting edge H as the curve B occupiesrelative to the original cutting edge A. The chisel is preferablymaintained in its reverse position only long enough to reverse the angleof the cutting edge to one having the same relative setting to thechisel as that originally provided. Upon this condition being reachedthe chisel is again returned to its original or normal position.

The means for locking the tongue to the chisel is constructed asfollows:

Extending lengthwise of and'disposed in a recess 6 formed in one side ofthe tongue is a flat spring 7 ,secured to the tongue at the end nearestthe outer end of the same and normally projecting outwardly from therecess at its opposite or free end, as shown in Fig. 5,

The free end of the sprin is adapted to project into either one of t eopposed recesses 8 formed in the sides of the socket-3,

pressed until it reaches the corresponding. end of the recess 8 wlfen'itwill snap out into said recess, and will thus prevent withdrawingmovement of the hisel from the tongue.

Such withdrawal ho ever can be easily accomplished when desired by deressing the sprin by' means of a nail or ot or tool inserted through thecorresponding hole 9 and holding the spring depressed while the is drawnoutwardly suflicient to move the free end of the spring beyond theadjacent end of the socket recess.

From the foregoing description it will be readily seen that I havefiproduced such a device as substantially ful Is the objects of theinvention as set forth herein. I While this specification sets forth indetail the present and preferred construction of the device, still inpractice such deviations from such detail may be resorted to as do notform a de arture from the spirit of the invention, as efined by theappended claims. Having thus described my invention what I- claim as newand useful and desire to secure by Letters Patent is:

1. A chisel for ground working implements chisel p comprising a baseportion adapted for attachment to a standard and a oint portion having atransversely exten ng cutting edge;

said point portion having its under surface" concavely curved from thecutting edge rearwardly acertain distance, and having its upper surfaceformed with a convex curvature comprising a base portion adapted forattachment to a standard and a point portion having a transverselyextending cutting edge; sald point portion having its under surface 5concavely curved from the cutting edge rearwardly a certain distance,and having its upper surface formed with a convex curvatureextendingrearwardly from the cutting edge, said convex curvature merging into aconcave curve disposed some distance rearwardly of the plane of theconcave curvature on the under side of the point.

3. A chisel for ground working im lements comprising a base rtion adaptefor at- 15 tachment to a stan ard and a point portion having atransversel extending cutting edge; said point portion aving its undersurface concavely curved from thecutting edge rearwardly a certaindistance, and having its up- 20 per surface formed with a convexcurvature extending rearwardly from the cuttingedge, said convexcurvature mergin into a concave curve disposed entirely be ow a straightline projected from the cutting edge to the 25 rear end ofthebase attheto In testimony whereof I a x m si ature,

J CH3 1. 0C RD.

